Combustion control means



Jan. 14, 5 5 WEEKS COMBUSTION CONTROL MEANS Filed July 5, 1932 5Sheets-Sheet l km W WM A

mm 9 E Jan, 14, HOBO.

COMBUSTION CONTROL MEANS s. 8. WEEKS Filed July 5, 1952 5 Sheets-Sheet 2Jan... M, 1%.. S 5, WEE I 2mm COMBUSTION CONTROL MEANS Filed July 5,1932 v 3 Sheets-Sheet 3 M H i /ai /ama Patented Jan. 14, 1936 UNITEDSTATES ATENT OFFICE 4 Claims.

This invention relates to combustion control means. More especially itrelates to means for controlling fire conditions in predetermined stepsrather than by a gradual increase or decrease and in particular theinvention has to do with improved adjusting means for a fuel regulatorand a draft compensator associated therewith.

It is an object of this invention to provide in connection withautomatic fuel controlling apparatus which functions on the step-by-stepprinciple, improved adjusting means which enable separate adjustments ofany one of the step actions to be made for that step alone withoutaffecting the firing conditions of any other step, albeit it is afeature of the invention to provide for the simultaneous adjustment ofall steps if that be desired.

It is also an object to provide in connection with a draft compensatorwhich operates on the counterbalanced damper principle, novel means forautomatically changing the counterbalance of the damper in accordancewith the draft conditions desired for each step effected by the fuelregulator.

It is a feature of the invention that the fuel supply is regulated by asingle control valve and that the same actuating means which regulatethe movements of this valve also effect the automatic adjustment of thedraft compensator and in such manner that an increase of draft throughthe furnace or boiler will take place before an increase of fuel supplyand a decrease of said draft will occur after the fuel supply is cutdown. This feature insures most favorable conditions for completecombustion during the change-over from one step to another.

The invention is herein particularly shown in its application to aliquid fuel system but this is merely illustrative of the principlesinvolved and it is to be understood that these principles may be appliedto other automatic firing apparatus and that it is intended to cover bysuitable expression in the appended claims whatever features ofpatentable novelty exist in the invention disclosed.

In the accompanying drawings:

Figure 1 is a front elevation of a boiler installation comprisingapparatus embodying the present invention;

Figure 2 is a side elevation of the upper portion of the boiler;

Figure 3 is a side elevation, in section as on line 3-3 of Figure 1, ofthe draft compensator;

Figure 4 is an elevation of the improved regulator;

Figure 5 is an elevation of a portion of this regulator showing therelative positions of the parts when a minimum fire is desired;

Figure 6 is another elevation in section of portions of the fuelregulator showing the relative positions of the operative parts when amedium fire is desired.

Figure '7 is a side elevation of the draft compensator showing itsadjustment corresponding to the position of the regulator shown inFigure 6; v

Figure 8 is still another sectional elevation of portions of theregulator, when the parts have been shifted for maximum fire conditions;and

Figure 9 is another side elevation of the compensator adjusted tocorrespond with the position of the regulator seen in Figure 8.

Referring more particularly to the drawings Figures 1 and 2 show aboiler l (which may be one of a battery) having a steam dome or header2, an uptake flue 3 and fluid fuel burners 4 of any desiredconstruction. A master controller of the type disclosed in United StatesLetters Patent 1,197,053 is connected to the steam header by pipe 5 andhas a controller unit 6 (6') for each step or fire condition to beestablished besides the lowest or minimum fire condition. For thepurpose of this case the apparatus disclosed is capable of producingthree different fire conditions-to be hereinafter termed minimum, mediumand maximumbut it is to be understood that any number of steps ordifferent fire conditions from two up may be attained by addingadditional units. The controller unit 6 is adjusted so that when apredetermined steam pressure occurs it will act to bring about theestab- I lishment of the medium fire condition and its companion unit 6'is adjusted to respond to a different steam pressure to produce themaximum fire condition.

The controller units 6, 6' are connected to a fluid pressure supply lineI and to a waste line or open drain pipe 8. Each unit 6, 6' is alsoconnected by pipes 9 and I0 respectively, to an improved regulator IIwhich embodies the novel fuel adjusting means of this invention. Inpipes 9 and ll] are restriction valves 30, and lila by which the flow offluid pressure to the regulator may be adjusted.

This regulator (see Figures 3 and 4) has a single control valve I2 ofthe piston type movable in an open ended cylinder l3 provided in thevalve body. In the wall of this cylinder is a triangular-shaped openingM, with vertex downward, which, when opened by the piston, establishesconnection between the main fuel supply line I5 and the pipe l6 leadingto the burners 4.

The piston valve is acted upon from below by a coiled spring H whichconstantly urges the valve upward, or in other words, tends to open thevalve by uncovering more of the triangular port M. The upper end of thevalve stem l8 has an adjusting nut 19 thereon which rests against anadjusting screw 28 associated with a cross-bar 2|.

This crossbar has an extended hollow hub Zia which telescopes a tubularpost 22 depending from the frame of the regulator. A coiled spring 23interposed between the frame and crossbar tends always to move thelatter toward the adjusting nut E9 on the stem of the piston valve, itsdownward movement being limited by its engaging the head 23a of theadjusting screw 26. This screw extends into the hollow of the tubularpost 22 and has at its inner or upper end a nut 24 which rests on aninternal annular shoulder 22a of the post. The post andhub are suitablyslotted, as at 221) and 2H) respectively, to accommodate a screw 25which extends through the slots into the nut 24 and prevents rotation ofthe latter while permitting axial movement thereof. By turning the screw20 the downward limit of the crossbar can thus be adjusted as desired.

The arms of the crossbar are provided with threaded holes Zlc, 2| (1into which are threaded duplicate adjusting screws 26, 26'. Each ofthese screws is associated with an assembly which is identically likethe other, and therefor but one of these assemblies will be described indetail. It is to be understood, however, that parts having a referencenumber with a prime added are identically like other parts having thesame number without the prime.

Attached to the frame, in axial alignment with the adjusting screws 26,26 are cylinders 21, 21 to whose upper ends are connected the pipes 9and i respectively leading from the controller units 6, 6. The lowerends of the cylinders are vented through pipes 28, 28 to any convenientdrain. Each cylinder is provided with a piston 29, 29 from which extendsupward through a suitable packing gland 39, 3G a hollow piston rod 3|,3!. Each piston head has an axial bore into the bottom end of which isthreaded a hollow screw 32, 32'.

In the hollow of each piston rod is another rod 33 (33) which has anenlarged upper end 33a (33's and extends downward through the screw 32(32') through a packing box 34 (34) and through the adjusting screw 26(26) being provided at its lower end with a nut 33b (33b).

When there is no appreciable demand for steam from the boiler bothcontroller units 6, 6 will be set so that the fluid pressure supply isconnected through pipes 9 and Ill with the cylinders 27, 21. Under suchconditions, the pistons 29, 29 are both held at the bottom of theirrespective cylinders by the fluid pressure therein. The crossbar will bein its lowermost adjusted position, seen in Figure 4, and the fuelcontrol valve l2 will be open only wide enough to maintain the minimumfire condition in the boiler. If now a load comes on the boiler whichcauses a drop of pressure sufficient to actuate the con troller unit 6,a valve thereof will be shifted to shut off the fluid pressure from pipe9 and connect the latter with the waste line 8. The release of pressurethus effected from cylinder 2'! will permit its piston to move to itsuppermost position, as seen in Figure 6, where it will remain until thefluid pressure is again admitted to the cylinder. As the piston movesupward, no change of the fuel valve !2 occurs until near the end of thepiston stroke, but then the screw 32 engages the enlarged end 33a of therod 33 and lifts the latter to bring its nut 3312 against the head ofadjusting screw 26. Movement of the latter carries with it the crossbarand as this moves upward, the piston valve follows under the influenceof spring ll, thus opening a greater portion of port M. The added fuelthus permitted to pass to the burner establishes the socalled mediumfire condition which of course effects a greater generation of steam inthe boiler. If the steam pressure as thus increased is sufl'icient tocarry the load, the parts will remain as shown in Figure until eitherthe load falls off or more steam is demanded.

If the load increases the other controller unit (5 responds to shut offthe fluid pressure to pipe l3 and connect it with the waste 8. As justdescribed, this permits piston 29' to move upward and near the end ofits stroke to effect further upward movement of its rod 33 and the crossbar 2| with consequent further opening of the port M, as shown in Figure8. This will establish the maximum fire condition and ought to result ina generation of steam in excess of the increased demand, it beingassumed that this latter demand is not the maximum of which the boileris capable of supplying. If the load is equal to or in excess of themaximum capacity of the boiler, the parts will remain as seen in Figure8 with the valve in its most open position.

In practice, however, an excess load is most unusual and the normalmaximum load can be more than satisfied by the boiler when the maximumfire conditions prevail. In fact, it is a feature of the invention thatthe regulator can be particularly adjusted to give a maximum firecondition which will exceed the maximum load normally encountered. Thisis accomplished by adjusting the screw 26 so that when its rod 33' israised by the piston as the crossbar will be lifted and the piston valveopened so as to supply sufficient fuel to keep the fire at the intensitynecessary to exceed the said load. Thus the invention provides for theindividual adjustment of the fuel control valve in accordance with thedemand of the maximum load.

If the load is reduced below the maximum and an excess of steam therebyresults, the controller unit 6 will respond to again connect pipe [0with the fluid pressure supply and thus cause piston 29 to descend toits lowermost position. As it starts downward, the rod 33' travels withit under the influence of spring 23 as exerted through the crossbar andscrew 26' on the nut 33b at the end of the rod. When the crossbarreaches the position where the adjusting screw 26 engages nut 33b on theother rod 33, the bar comes to rest. Thus the piston valve is returnedto its intermediate position corresponding to medium fire conditions.Here again the invention provides for individual adjustment to obtain apreferred medium fire condition. By adjusting the screw 25 the positionof the crossbar and necessarily the piston valve !2 can be determined asdesired.

If the demand for steam is further reduced and the medium fire conditionno longer needed, the controller unit 6 thereupon connects pipe 8 withthe fluid pressure supply thus bringing about the downward travel ofpiston 29 and a further closing of the fuel supply valve l2. To adjustthe latter fora desired minimum fire condition, screw 20 can be turnedin its nut 24 to vary the relative position of the screw with respect tothe frame. Adjustment of this screw 20 also changes the positions of thecrossbar and the two adjusting screwsZB, 285' but note that no change ismade in respect to rods 33 and 33 because of the lost motion providedbetween screws 26, 26 and nuts 33b and 33'b respectively. And when theselatter nuts are again raised by subsequent operation of the pistons,they will again set the piston valve in the same position as beforedescribed for medium or maximumfire conditions. Thus it is that theinvention provides for the individual or separate adjustment for eachfire condition without any effect on the settings for the other fireconditions.

If it should be determined that the piston valve shouldbe opened widerfor all fire conditions, as when the burner begins to clog up or adifferent fuelis used, this may be accomplished by simply adjusting thenut IS on the end of the piston valve stem l8. This varies the positionof the valve I2 with respect to the crossbar 2| so that when the latteris positioned by the operation of the pistons the supply valve will beopened more or less in accordance with the setting of the nut I9. Thusthe invention provides for the simultaneous adjustment of all fireconditions if desired.

In well equipped boiler installations today it is desirable to have whatis known as a draft compensator. for counteracting the varying effectsin the air flow caused by conditions beyond the control of theapparatus. For example, changes in atmospheric conditions, change influe gas temperature, changes in the number of boilers operating or inthe number of burners used all influence the draft and of course thewind factor is a variable that is almost continually in action. Theusual draft compensator is a nearly counterbalanced-damper controllingwhat may be called an auxiliary'opening into the gas passage of theboiler. This damper may be on the supply side of the fire box whenforced draft is used or in the discharge flue if natural draft or ablower on the discharge side is relied upon for induced air flow throughthe furnace. These compensators may be set or adjusted initially for anydesired air flow through the furnace and, so long as this particular airflow is maintained, are generally satisfactory. But if a different airflow through the furnace is desired and the compensator is not againadjusted. for this changed air flow, the compensator will at once becomea source of trouble rather than a helpful device. In other words, if thecompensator is initially adjusted for the air flow through the boilerwhen a minimum fire is maintained, it will act as a true compensatoronly so long as this air flow continues. If the fuel supply is increasedto produce a medium or maximum fire condition, it is necessary toincrease the air flow through the furnace correspondingly. If this isattempted with the ordinary compensator, the latter opens wider and theresult is that more air is taken in from the outside beyond the boiler,or more air is deflected out of the air passage if the compensator isbetween the forced draft blower and the furnace. In either case thedesired increase of air flow actually through the boiler is notaccomplished and incomplete and ineffective combustion results.

The present invention avoids such an undesirable result by providing forthe automatic adjustment of a compensator in keeping with the air flowchange accompanying a change in fire conditions. Moreover, it effectsthe automatic adjustment of the compensator in a manner most favorableto the changing fire conditions.

The upper ends of the piston rods 3|, 3! are I connected to chain 35which extends through casings 36, 36 at the top of the regulator. Thischain is provided with adjustable stops 31, 31 which engage the ends ofits respective casings and enable the stroke of each piston to beadjusted. Chain 35 passes over a sprocket 38 journaled at the bottom endof a rod or cable 39. The latter is attached to a lever it on a shaft Mwhich also carries another lever 42. These levers are of differentlengths so that the linear travel of the end of the shorter lever may bemultiplied in the linear travel of the end of the longer lever. To thelatter is attached another chain or cable 43 which passes around agrooved pulley A4 and leads to levers 45, 56 mounted on the compensator.

This draft compensator has a simple damper 41 mounted near its ends on ahorizontal axle 48 at the lower edge of an auxiliary opening 49 into theflue 3. (See Figure 3.) Attached to the damper proper is a plate 553having an arcuate slot 59a concentric with the axle 48. The levers 55,46 and a third lever 5| are mounted rotatably on the axle 48 and are sodisposed that they may swing beside the plate 50. In the slots Ella arestop pins 52, 53, 54, one for each of the levers. The latter are'providedwith weights 45a, 35a and Ella respectively which are manuallyadjustable along the said levers to vary the counterbalancing effect ofeach on the damper proper. The latter with its plate and stop pins arefirst counterbalanced by a suitable weight 52 and then stop pin 54 isadjusted so that when lever 5i rests against it, the weight of the leverwill counteract the force of the air draft on the damper when the latteris open approximately 45 as seen in Figure 3. This is the desiredposition of the damper when a minimum fire condition prevails. If theflue draft fluctuates, the damper swings in or out to let in more orless air through opening G9 and thus keep the draft through the boilersubstantially constant.

If now the load on the boiler demands a medium fire condition theregulator acts as heretofore described to permit piston 29 to rise andopen the fuel valve to admit more fuel to the furnace. This necessitatesan increase of air flow through the furnace and this the inventioninsures :by automatically adjusting the draft compensator.

As the piston 29 moves upward through its stroke sprocket 38 is alsodrawn upward by the cable 39 acting under the combined influence of aweight 55 on shaft M and the weighted levers 45 and 46. But the sprocketwill move upward only one-half the length of the piston stroke becausewhile the chain 38 on one side of the sprocket is moving upward, theother end of the chain remains still, and so the sprocket can travelupward only one-half the travel of the piston. This upward movement ofthe sprocket and rod allows shaft 4| and levers 4i] and 52 to turnsufliciently to lower the weighted levers s5 and 46 so that lever 46rests on its stop pin 53 on the damper plate. This at once adds morecounterbalance against the air flow through opening 49 and causes thedamper to swing to the position indicate-d by the dot and dash line plin Figure 3 and actually shown in Figure '7. Accordingly, less air willbe drawn in through the opening and more air will pass through theboiler.

Likewise if the other piston 29 is raised to establish maximum firecondition, its piston rod moves upward and again the sprocket ascends adistance equal to one-half the travel of the piston. But this is enoughto allow the third weighted lever 45 to rest on its stop pin 32 and thusimpose another additional counterbalance on the damper. This causes thedamper to swing to the position indicated by the dot and dash line 102in Figure 3 and shown in Figure 9. With the damper thus more nearlyclosed still less air will enter through opening 49 and still more willpass through the boiler.

It is of course understood that in adjusting the weights 45a, 46a and amon the respective levers each will be set so that its counterbalancingeffect on the damper will correspond with the desired air fiow throughthe fire box, but after once so set, the levers themselves will beautomatically lifted or lowered as the apparatus operates to establishthe desired fire condition. And it is to be noted that when a pistonrises to increase the fire its respective lever is lowered to its stoppin before the control valve is actually opened to supply more fuel.This is so because as soon as the piston starts to move upward itscounterbalancing lever begins to descend and will have reached the stoppin before the contact screw (32, 32') in the piston head has engagedthe shoulder on the rod (3|, 3|). Conversely when either piston movesdownward to reduce the fire condition, the control valve is shifted toits more closed position before the respective weighted lever is liftedclear of the stop pin. Thus it is that the automatic adjustment of thecompensator occurs before the valve is opened wider and after it hasbeen partly closed.

Where rather violent and extremely sudden changes in the flue draft areapt to occur, it may be beneficial to employ a light brake on thecompensator such as the dash pot 56 shown in Figures 1 and 2. This is asimple cylinder with a piston therein whose rod 51 is connected by alink 58 and crank 59 to the axle shaft 48. The opposite ends of thecylinder are connected by a bypass 60 of restricted size which enablesthe fiuid in the cylinder to be transferred from one side of the pistonto the other with retarding or braking effect on the damper movements.

Although the drawings disclose but a single boiler, it is to beunderstood that the control apparatus as a whole may be applied toseveral boilers. Each would have its own valve control unit and its owncompensator, but all might be connected to the same steam actuatedmaster controller in which event the latter would receive its pressureinfluence from a common steam header into which the several boilerswould be connected. Thus the control valve units of each boiler andtheir respective draft compensators can be adjusted in accordance withthe characteristics of the individual boiler, the apparatus being setfor each fire condition as respects both the fuel feed and the desiredaction of the draft compensator.

I claim:

1. Combustion control means for a boiler comprising, in combination,mechanism for regulating the feed of fuel to the furnace; apparatus forcompensating the gas flow through the boiler comprising an opening inthe passage for said flow; a free-swinging counterbalanced damper insaid opening movable in response to changes of pressure of said gas; andmeans actuated by the said regulating mechanism for changing thecounterbalance of said damper in accordance with the regulation of saidfuel.

2. Combustion control means for a boiler comprising, in combination,mechanism operating on the step-by-step principle for regulating thefeed of fuel to the furnace; apparatus for compensating the gas flowthrough the boiler comprising an opening in the passage for said flow; afree-swinging counterbalanced damper in said opening movable in responseto changes of pressure of said gas, and means for changing thecounterbalancing weight of said compensator with each step in theregulation of the fuel.

3. Combustion control means for a boiler comprising, in combination,mechanism for regulating the feed of fuel to the furnace; a draftcompensator comprising an opening in the passage for gas flow throughthe boiler, a free-swinging counterbalanced damper in said openingmovable in response to changes of pressure of the gas flowing in saidpassage; means actuated by the said mechanism for changing thecounterbalance of said damper in accordance with the regulation of fuel;and braking means associated with said damper.

4. Combustion control means for a boiler comprising a draft compensatorhaving a free-swinging counterbalanced damper movable in response tovariations in pressure of the gas flowing through the furnace; and meansfor changing the counter-weight of said damper to correspond withpredetermined changes in the fire conditions of said boiler. 55

SHIRLEY S. WEEKS.

